Fuel injection nozzle

ABSTRACT

A fuel nozzle structure for a combustion chamber, the downstream portion of the nozzle structure having a plurality of hollow nozzle inserts disposed therethrough, and a nozzle cover in spaced relation with the downstream nozzle portion and defining a cooling air passageway therebetween. The nozzle inserts project into apertures in the nozzle cover so that fuel can be projected through the cover and into the combustion chamber and the inserts being in spaced relation with the cover so as to allow cooling air flowing through the passageway to flow into the combustion chamber. This fuel nozzle structure prevents residues from collecting on the downstream nozzle portion.

United States Patent [191 Mori [5 4] FUEL INJECTION NOZZLE [75] Inventor: Yoshitaka Mori, Tarumi-ku, Kobe,

Japan [73] Aslsignee: Mitsubishi Jukogyo Kabushiki l Kaisha, Tokyo, Japan [22 Filed: Sept. 29, 1971 [21] Appl.No.: 184,676

[30] Foreign Application Priority Data Nov. 30, 1970 Japan ..45/118098 [52] U.S. Cl ..239/419.5, 239/406 [51] Int. Cl. ..F23d 13/40 [58] Field of Search ..239/399, 403, 405,

[56] References Cited v UNITED STATES PATENTS 3,153,438 10/1964 Brzozowski ..239/405 X 3,211,207 10/1965 Luft .239/406 r 111 L IN i Primary ExaminerRichard A. Schacher Attorney-A. T. Stratton, F. P. Lyle, F. Cristiano Jr. et a1.

[57] ABSTRACT A fuel nozzle structure for a combustion chamber, the downstream portion of the nozzle structure having a plurality of hollow nozzle inserts I disposed therethrough, and a nozzle cover in spaced relation with the downstream nozzle portion and defining a cooling air passageway therebetween. The nozzle inserts project into apertures in the nozzle cover so that fuel can be projected through the cover and into the combustion chamber and the inserts being in spaced relation with the cover so as to allow cooling airflowing through the passageway to flow into the combustion chamber. This fuel nozzle structure prevents residues from collecting on the downstream nozzle portion.

5 Claims, 5 Drawing Figures 2 Sheets-Sheet 1 FIG.

PRIOR ART FIG.

FUEL INJECTION NOZZLE BACKGROUND OF THE INVENTION The present invention relates to combustion chambers for gas turbines, and more specifically to the fuel nozzle structures disposed therein. One of the problems with conventional fuel nozzle structures used in combustion chambers is that the downstream portion of the nozzle is exposed to the very high temperature region within the combustion chamber and the downstream portion therefore becomes exceedingly hot. The high temperature of the downstream nozzle portion causes the volatile components in the fuels to leave viscous solid residues to adhere on the inner or upstream surface of the downstream nozzle portion. Once some of these solids accumulate on the nozzle downstream portion, the residue further accumulates on the initial deposited residue. Residues continue to adhere and accumulate to eventually begin to block the nozzle apertures.

In turn, the downstream nozzle portion, as a consequence of the accumulation of residues on the upstream side of the downstream nozzle portion, becomes more heated since the residues prevent the nozzle from being properly cooled. Furthermore, the accumulation -of the residues at the fuel injection apertures creates uneven fuel flow and produces a greater pressure loss, even though the apertures are designed so that the pressure losses will be at a minimum. To maintain the desired quantity of fuel, the pressure to supply the fuel must be raised to make up for the loss equivalent to the decrease in the area of the apertures. The increase in pressure produces an increase in the power consumption of the compressor, and an overall decrease in turbine efficiency results.

Often times, the residue contains considerable amounts of corrosive substances, such as sulfur, and the high temperature of the nozzle promotes the corrosion of the base material of the nozzle resulting in a shutdown of the turbine. The nozzle must be regularly detached for the purposes of cleaning and replacement, and it is extremely difficult to replace the nozzle during operation because thecombustion chamber within the turbine is normally surrounded with pressurized air. It is a severe disadvantage to the gas turbine power plant to stop the turbine to replace the nozzle.

It would be desirable then to devise a nozzle structure which would prevent residues from forming on the nozzle, and furthermore to allow proper cooling thereof.

SUMMARY OF THE INVENTION A combustion chamber having a nozzle structure dis posed therein at the downstream end thereof. At the downstream end of the nozzle structure is a plurality of fuel exit apertures in which is disposed a corresponding plurality of nozzle inserts to inject fuel from the nozzle structure into the combustion chamber. Also disposed around the downstream end of the fuel nozzle is a nozzle cover structure in spaced relation with the nozzle and defining a cooling fluid passageway therebetween. The nozzle inserts project into corresponding apertures in the nozzle cover and are in spaced relation with the nozzle structure to allow cooling fluid to pass through the passageway and out through the apertures in the nozzle cover.

The nozzle cover prevents the nozzle from being exposed to the very high temperature of the combustion chamber, and, by defining a passageway therebetween, allows for cooling fluid to cool the nozzle structure. This minimizes the amount of solid residues which are deposited on the nozzle structure and further prevents the clogging of the fuel passages. Far less maintenance is required on the nozzle structure and corrosion of the nozzle structure is minimized. The operating life of the nozzle structure is substantially increased enabling a substantial continuing generating of power from the turbine power plant.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a longitudinal sectional view of a portion of a gas turbine power plant having a conventional nozzle structure;

FIG. 2 shows a longitudinal sectional view of a portion of a gas turbine power plant having a nozzle structure build in accordance with the present invention;

FIG. 3 shows an enlarged portion of the nozzle structure shown in FIG. 2;

FIG. 4 is a view taken along line IV--IV in FIG. 3; and

FIG. 5 is a' longitudinal view of another embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings in detail and more specifically to FIG. 1, there is shown a portion of a gas turbine combustion section 10 comprising an annular outer casing structure 11 and a portion of the combustion chamber 13, disposed concentrically therein. The combustion chamber 13 has a fuel nozzle structure 15 which is detachably secured to the upstream portion of the combustion chamber 13. The combustion chamber 13 is secured to an annular combustor holder 16 which, in turn, is secured to the vertical wall portion of the outer casing 11. An annular baffle swirler structure 18 is secured to the vertical wall of the outer casing 1 l and is disposed between the combustor holder 16 and the fuel nozzle 15, in spaced relation therebetween. A plurality of apertures 20 are radially disposed in the combustion holder 16 to provide fluid communication between a plenum chamber 22 and a passageway 23, which leads to the combustion chamber 13.

A plurality of apertures 25 are disposed around the baffle swirler 18 which allows cooling air from passage way 23 to flow therethrough into the combustion chamber.

The conventional fuel nozzle structure 15 is comprised of a downstream nozzle tip portion 27, having fuel apertures 28 disposed therearound to admit fuel into the combustion chamber 13.

As previously described, the fuel nozzle 15 has the downstream surface of the nozzle tip 27 exposed to the high temperature region in the combustion chamber and thereby becomes exceedingly hot, primarily due to the radiation generated from the flame. Consequently, fuel residues collect on the upstream surface of the nozzle tip 27 and continue to build up' until the fuel injection apertures 28 become partially blocked. This results in a pressure loss, and inefficient gas turbine operation, and the residue, in fact, prevents proper cooling of the nozzle tip portion 27. Finally, corrosion is promoted on the base material of the nozzle tip 27 and reg ular cleaning and replacement are necessary, resulting in stoppage of the gas turbine power plant.

Referring to FIG. 2, there is shown a partial view of a combustion chamber 34 similar to that shown in FIG, 1, where represents the outer casing of the combustion portion of the gas turbine power plant. An annular holder structure 31 is secured to the casing 30 by any suitable means such as bolts 32. The upstream domeshaped portion of the combustion chamber 34 is secured to the radially inner surface of the holder 31.

A baffle swirler structure 36 is also secured to the outer casing structure 30 and is in spaced relation with the holder 31. The baffle 36 is in spaced relation with the dome portion of the combustion chamber 34 jointly defining annular passageway 37.

A fuel injection nozzle structure 39 is secured to the outer casing 30, by any suitable means such as bolts 41. The nozzle projects into the dome portion of the combustion chamber 34. The downstream tip portion 42 of the nozzle 30 is protected by a nozzle cover structure 43, which is disposed in a spaced relation with the nozzle tip 42 and, cooperatively therewith, defines passageway 45. The nozzle cover 43 is secured to the baffle swirler structure 36, by any suitable means such as bolts 46.

A plurality of circumferentially spaced radial apertures 48 are disposed around the holder 31 to provide fluid communication between a pressurized plenum chamber 50 and the passageway 37. The chamber 50 is partially defined by the outer casing 30 and the combustion chamber. Furthermore, disposed around the baffle swirler structure 36 is a corresponding plurality of air inlet apertures 50. Corresponding thereto is a plurality of smaller air inlet apertures 52 disposed circumferentially around the nozzle cover 43 to permit fluid communication with the cooling air passageway 45.

On the downstream portion of the nozzle tip 42, are a plurality of hollow nozzle insert structures 53 dis.- posed in corresponding apertures in the nozzle tip. As best seen in FIG. 3, the nozzle inserts 53 are screw threaded into the body of the nozzle tip 42 and project through the air cooling passageway 45 and into a corresponding aperture 54 in the nozzle cover 43. The insert 53 is in spaced relation with the nozzle cover 43 and defines an annular gap 56. The inner wall portion 58 of the insert 53 is flared at the downstream portion of the insert to thereby increase the cross-sectional area at the downstream portion of the insert. A cooling fin 60 (FIGS. 3 and 4) is disposed around the downstream portion of the insert 53.

In operation, cooling air passes from the plenum chamber 50 (FIG. 2) through apertures 48 into passageway 37, a portion of the air also passing through apertures 50. The cooling air through apertures 50 passes through apertures 52 into passageway 45. The cooling air passes through the apertures 48, 50 and 52 because of the pressure differential between the plenum chamber 50 and the combustion chamber 34. The air flowing into passageway 45 continues therethrough and passes through gap 56 (FIG. 3) and then out the aperture 54 in the nozzle cover 43. Fuel, meanwhile, is passing through the fuel injection nozzle structure 39 and is injected through the nozzle insert 53 into the combustion chamber 34. The cooling air around the nozzle insert 53 at gap 56 easily flows out into the combustion chamber, because it is absorbed in the fuel flow by an ejector effect. The cooling fin 60 protects the outer casing 62, and the combustor 64. An annular baf- I fle swirler structure 66 is securedly fastened within the combustor 64 anda nozzle cover 68 is provided between the baffle structure 66 and the nozzle 65. Disposed at the downstream tip of the nozzle are the nozzle inserts 70, which are disposed in a similar manner to that described in connection with FIG. 2. This embodiment is designed so that pressurized air in the plenum chamber 63 passes through a cooling structure 72, as indicated by the dashed connection 71, and then into a cooling flow passageway 73 in the nozzle structure 65. The cooling flow passageway 73 is in fluid communication with air flow passageway 74 which provides the cooling air to the nozzle tip portion 69. This eliminates apertures in the nozzle cover such as those shown at 52 in FIG. 2 and provides for cooler air to thenozzle tip.

In both of the embodiments shown, the outer surface of the nozzle tip is not directly exposed to the high temperature flame within the combustion chamber. The nozzle tip therefore operates at a substantially lower temperature than conventional nozzles. This prevents the accumulation of solid residues on the inner surface of the nozzle tip. In conventional nozzles, fuel residues such as tars are deposited on the hot nozzle surface and tend to carbonize, building up a hard solid deposit with the increased fuel pressure loss and corrosive effects previously discussed. The improved nozzle tip herein disclosed runs much cooler and no solid residues build up on it, so that the undesirable effects of such deposits do not occur. The disclosed nozzle can be utilized in a combustion chamber for a much longer period of time without being cleaned or replaced and, correspondingly, the gas turbine power plant can operate for a far longer period of time than at present.

Although more than one embodiment has been shown, it is intended that all the matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

l. A combustion chamber having a fuel nozzle structure to inject fuel therein,

said nozzle structure having a downstream nozzle tip portion,

a nozzle cover structure surrounding the downstream tip portion of the nozzle, said cover structure shielding the nozzle tip portion from the heat generated in said combustion chamber,

the downstream wall of said nozzle tip portion having a plurality of apertures, and said nozzle cover structure having a corresponding plurality of apertures.

2. The structure recited in claim 1, and further including a plurality of nozzle'insert structures disposed in the apertures in the nozzle tip,

said nozzle inserts projecting into the apertures in the nozzle cover.

3. The structure recited in claim 2, wherein the nozzle inserts are fastened to the nozzle structure and 6 wherein the nozzle inserts are in a spaced relation relaapertures in the nozzle tip and fastened to the tip, tive to the nozzle Co ersaid insert structures projecting into the correspond- 4. The structure recited in claim 2 and further including cooling means for the nozzle inserts.

The fip melted p wherem F 5 the apertures in the nozzle cover being .in fluid comzle cover is in spaced relation with the nozzle tip definh ing the cooling air passageway therebetween, mumcauot'l t coo mg f w to means to supply cooling air to said passageway allow cooling air to flow through said passageway a plurality of corresponding apertures in the nozzle and 531d apertures mm the Combustion chamber to tip and the nozzle .cover, 10 cool the nozzle tip and nozzle inserts. a plurality of nozzle insert structures disposed in the ing apertures in the nozzle cover and in spaced relation therefrom, 

1. A combustion chamber having a fuel nozzle structure to inject fuel therein, said nozzle structure having a downstream nozzle tip portion, a nozzle cover structure surrounding the downstream tip portion of the nozzle, said cover structure shielding the nozzle tip portion from the heat generated in said combustion chamber, the downstream wall of said nozzle tip portion having a plurality of apertures, and said nozzle cover structure having a corresponding plurality of apertures.
 2. The structure recited in claim 1, and further including a plurality of nozzle insert structures disposed in the apertures in the nozzle tip, said nozzle inserts projecting into the apertures in the nozzle cover.
 3. The structure recited in claim 2, wherein the nozzle inserts are fastened to the nozzle structure and wherein the nozzle inserts are in a spaced relation relative to the nozzle cover.
 4. The structure recited in claim 2 and further including cooling means for the nozzle inserts.
 5. The structure recited in claim 1, wherein the nozzle cover is in spaced relation with the nozzle tip defining the cooling air passageway therebetween, means to supply cooling air to said passageway, a plurality of corresponding apertures in the nozzle tip and the nozzle cover, a plurality of nozzle insert structures disposed in the apertures in the nozzle tip and fastened to the tip, said insert structures projecting into the corresponding apertures in the nozzle cover and in spaced relation therefrom, the apertures in the nozzle cover being in fluid communication with the cooling air passageway, to allow cooling air to flow through said passageway and said apertures into the combustion chamber to cool the nozzle tip and nozzle inserts. 